The first HMS Mersey was a Conway-class 20-gun sixth rate post ship, launched in 1814; she was re-rated as 26 guns in 1817. She was too late to see action in the Napoleonic War, though she nevertheless had a long and distinguished career that took her to Halifax Station in 1818, then joining the South American station in 1824 till its departure in 1827, when she was then deployed to the Caribbean station from that year until 1831. She was eventually broken up in 1852.